Basic Concepts: Progress, Primitive and Advanced

This is a repost of a piece I wrote for The Panda's Thumb in April 2004. I add it here to put it in the Basics series.

One of the more difficult conceptual problems the layperson has with biology lies in the simple word "primitive". It has many antonyms - "modern", "evolved" and "derived", and like many biological uses of ordinary words, everybody thinks they understand it, and doesn't.

It is a word from the Latin, of course, for "first fruits" or "first things of their kind", but in modern use it means "simple" or "undeveloped". And this is not - quite - what it means in biology.

It got its modern sense via the early 19th century social philosophy of a fellow named August Comte, who thought that societies evolved through predetermined stages - the theological, the metaphysical, and the scientific (thus starting the movement known as positivism). His ideas impressed a legal professor at Cambridge, Henry Maine, who concluded the society had society had passed through definite stages, from "primitive" to "progressive"; and these ideas spread from there.

Progress was then, as now, in the air. Things could only get better, and change of society was forced to improve. No sudden reversals... only improvement. It is obvious, therefore, how such ideas (which collectively go by the name The Great Chain of Being, shown right, from Raymond Lull in the 16th century) would be transferred over to the living world when evolution, or transmutation as it was called, got applied to life. What was true of the political world had to be true of the living world also.

This is exactly how the two founders of evolution over time applied the Great Chain - Jean Baptiste de Lamarck, and Erasmus Darwin. That's right, Erasmus, not Charles; his grandfather was one of the first people to propose evolution. For Lamarck and Erasmus Darwin, life began simple and unorganized, and got more complex and sophisticated in what they could do. Eventually, of course, we came along, and behold! We were the pinnacle of evolution, weren't we (if we happened to be white European males of property, at any rate)?

But then along came Charles Darwin, and Alfred Russel Wallace, and they had a different notion of progress. In fact, they had only a local notion of it. Things, if they got better, did so locally and relatively. And they could do badly too... they could go extinct, a possibility not acceptable under the Great Chain (the good God would never permit part of his creation to disappear). Groups of organisms, or taxa, as they came to be known in the 20th century, could become hard to find. There could be, in other words, a dearth of taxa.

It is famously understood that Darwin used a tree diagram (above, from the Origin) to represent evolutionary relationships. But tree diagrams can mislead. Darwin knew this - he had himself documented barnacles that became simpler as they evolved, not more complex, and he wrote to himself in a margin of a book "never say higher or lower" (advice he disregarded, by the way). We tend to think more like Lamarck or the first Darwin and think that something earlier in the evolutionary tree was somehow "not as good" as the modern taxa in that tree. But all that is required in Darwin's scheme is that each new species is better adapted to local conditions than the older ones. There is no insistence upon transitivity - if each species is better adapted at local conditions than its predecessors, it doesn't follow that the last in a series of species is better overall than the first in the series. Each species is well-adapted to its own conditions.

In the mid 20th century, a German entomologist named Willi Hennig (1950, 1966) proposed a way to classify taxa that was deliberately founded on Darwin's scheme of evolution. He used the characters of organisms and arranged them so that the more inclusive forms could be seen as those of the ancestors. Hennig coined many words from the Greek to replace the older and confusingly ambiguous terms. Two in particular were important.

Hennig defined the ancestral character with an adjective: plesiomorphous. This Greek term means "neighboring form", because it is shared by all the neighbors on the tree. Any character than is derived from the plesiomorphy is a version of it, but is changed. These he called apomorphous, from the Greek prefix that means "away from" + "form". Apomorphies defined branches on the evolutionary tree that had, by Ockham's Razor, likely changed later than the plesiomorphies that all the rest of that tree shared.

Hennig's terms remove the implications of Comte's view of history or the Great Chain. Evolution is now seen as a change from one form shared by all the other branches except those that have forms derived from it. There is no implication that this gets the species that share that trait a little closer to God, or perfection, or white European males.

By focusing on the traits of organisms, some have felt that Hennig's approach is a reversion to the older philosophy known as typology that preceded Darwin, and in a way, that is true. But this is not necessarily a flaw. The Canadian historian of biology Mary P Winsor (2003) recently pointed out that typology was in fact very similar to the modern approach of finding examples that approach the mode of a population. She calls this the "method of exemplars" and to my mind it really does capture what taxonomists were doing before, and after, Darwin.

So, "primitive" has been effectively abandoned by most biologists (Ayala 1988, Gould 1996, Mittelstrass et al. 1997), and those who do use it, are careful to avoid implications of progress in evolution (but see Ruse 1996).

References

Ayala, Francisco Jos�. 1988. Can 'progress' be defined as a biological concept? In Evolutionary progress, edited by M. H. Nitecki. Chicago: University of Chicago Press.

Gould, Stephen Jay. 1996. Full house: the spread of excellence from Plato to Darwin. New York: Harmony Books.

More like this

Readers may be somewhat surprised that Evolving Thoughts hasn't made much of the Darwin bicentennial and the Origin sesquicentennial so far. Well, I haven't needed to, given the number of other folk making hay from this. In particular I recommend Carl Zimmer's piece, over at his new digs with…

Taxonomy - the science of classifying organisms into putatively natural groups - is often treated as a kind of necessary bit of paperwork without much theoretical import by some biologists. Others think it is the single most important thing to do, usually justifying it in terms of conservation…

The French have always had an affinity for developmental models of historical processes. Comte famously argued that societies had four stages to go through. Lamarck held that species were like individual organisms that had a youth, maturity and senescence. And more recently Teilhard held that…

[This started as a discussion of the debate mentioned below. It got lost somewhere, and became me riffing on my favourite topics. Sorry.]
I love it when people I know have a barny* in public, but it presents some delicate choices and sensibilities to be honoured. The case in point today is…

Nice to see Grandpops Erasmus getting a mention, he all too often gets ignored by people talking about the origins of evolution. Charlie had a really impressive pair of grandfathers. What about a basics post on theories and mechanisms of evolution to stop people talking about CD having discovered/invented THE theory of evolution a form of expression that drives me up the wall.

Donate

Scienceblogs is part of Science 2.0, a pro-science outreach nonprofit operating under Section 501(c)(3) of the Internal Revenue Code. Please make a tax-deductible donation if you value independent science communication, collaboration, participation, and support open access.

You can also shop using Amazon Smile and though you pay nothing more we get a tiny something.

More by this author

So it is farewell...
I have enjoyed blogging here at Seed, who have been generally very good to me given the constraints of herding cats with string they are working under, but it is time to move on. The neighborhood became a little hostile to old fashioned fogies like me, and that's all we need to…

There's some reorganising of my life and blogging going on. I'll announce all the changes to links and stuff in a fortnight or less. Please excuse the dust and noise of the construction behind the plastic sheets.

In addition to the "missing link" trope that is being dished out about the new primate fossil, is another one, more subtle and insidious: it's the ancestor of all primates. How do they know that? Consider a biologically realistic scenario: at the time there were probably hundreds of species of…

More reads

Three statisticians go hunting for rabbit. They see a rabbit. The first statistician fires and misses, her bullet striking the ground below the beast. The second statistician fires and misses, their bullet striking a branch above the lagomorph. The third statistician, a lazy frequentist, says, "We got it!"
OK, that joke was not 1/5th as funny as any of XKCD's excellent jabs at the frequentist-…

“And there is the headlight, shining far down the track, glinting off the steel rails that, like all parallel lines, will meet in infinity, which is after all where this train is going.” -Bruce Catton
At the end of each week here at Starts With A Bang, it's important to take a look back at all we've gone through, and give some time and energy to all your thoughts on it. This week, there have been…

"I conclude, therefore, that this star is not some kind of comet or a fiery meteor... but that it is a star shining in the firmament itself one that has never previously been seen before our time, in any age since the beginning of the world." -Tycho Brahe
I want to take you back in history, back to the middle of the 1500s. Night skies were spectacular, even from the world's most cosmopolitan…